1. Field of the Invention
The present invention relates generally to bearing seals and particularly to ultra-low friction bearing seals useable in low torque miniature mechanical mechanisms.
2. Description of the Related Art
It is known to provide bearing shields and seals between inner and outer bearing races for protecting bearings located therebetween. Since bearing shields do not fully contact both the inner and outer races, certain contaminants can enter the bearing increasing friction and decreasing the useful life of the bearing. Presently available bearing seals consist of a single semi-rigid disk that is held in placed in the outer race by a fine wire retaining ring. A hole in the center of the disk clears a step on the inner race. While these seals are designed to contact both the inner and outer races, they present a number of problems. The fine wire retaining ring can pop loose causing catastrophic failure. Additionally, these seals can allow contaminants to pass therethrough, are subject to high friction torque and are not versatile over a wide range of operating conditions.
U.S. Pat. No. 2,600,434 to Saywell discloses a bearing seal including inner and outer washers which can be biased against one another. These washers are held in position either by retaining rings or by fixed attachment directly to one of the inner or outer races. The washers are made from a "spring" metal material.
U.S. Pat. No. 2,914,365 to Spicacci discloses a bearing seal made from a single washer which is snap-fitted between inner and outer races. This design is susceptible to large fluctuates in friction generated torque due to concentricity, alignment and tolerances of the bearing races as well as axial shifting. Spicacci also discloses the use of a retaining element to aid in keeping the seal in place. This retaining element requires the inner race to be made longer than standard boundary dimensions.
U.S. Pat. No. 4,687,349 to Pachuta discloses a bearing having a labyrinth seal and full-contact seal which cooperates with a shield. This construction is complex and therefore costly. Additionally, the elements of the seal which contact the inner and outer races are fixedly attached thereto.
A need is therefore identified for an improved bearing seal overcoming the above-described limitations and disadvantages of the prior art.